# 数据分组操作

代码：

```python
from itertools import groupby
from operator import itemgetter

# 希望按日期分组,(如果things中分组key不连续，需要先排序，因为groupby是按照连续项进行分组)
things=[('2012-05-21',11),('2012-05-21',3),
        ('2012-05-22',10),('2012-05-22',4),('2012-05-22',22),
        ('2012-05-23',33)]

#日期，itemgetter(0)为group key，此时要保证其是排序好的
for key ,items in groupby(things,itemgetter(0)):
    print('group key:',key)
    print('items:')
    for subitem in items:
        print(subitem)
    print('-'*20)
```

结果：

```python
group key: 2012-05-21
items:
('2012-05-21', 11)
('2012-05-21', 3)
--------------------
group key: 2012-05-22
items:
('2012-05-22', 10)
('2012-05-22', 4)
('2012-05-22', 22)
--------------------
group key: 2012-05-23
items:
('2012-05-23', 33)
--------------------
```

视频：

```
wait
```


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